Tobacco use continues to be the leading preventable cause of mortality in the United States, despite a decrease in the overall prevalence of cigarette smoking. In this issue of JAMA Internal Medicine, Siegel et al1 report that cigarette smoking continues to be the attributable cause of death for nearly half of people dying of 12 different cancers and notably 80% of people dying of lung cancer. Recent data also suggest that focusing only on mortality from conditions in which causal relationships have been established underestimates smoking-related mortality because an additional 17% of excess smoking-related mortality is associated with causes not formally established as attributable to smoking.2